We are requesting 5-year support in order to continue our studies of experimental induction and reversal of depression in rhesus monkeys. We propose to use a variety of techniques to produce depressive behavior, including social separations, vertical chamber confinement, and various learned helplessness paradigms. We will employ numerous indices to assess the degree of depression in the monkey subjects, including social-behavioral scoring, performance on learning tasks emphasizing cognitive and motivational variables, and certain physiological measures including CSF. Finally, we will test the efficacy of selected rehabilitative techniques, including monkey therapists, ECT, and antidepressant drugs, both those currently in clinical use and those which are presently experimental in nature. These studies will be carried out on infant, adolescent, and adult rhesus monkeys which have had a variety of early social histories.